1. Field of the Invention
The invention relates to nonwoven wet wipes and more specifically to nonwoven wipes impregnated with an aqueous non-alcoholic composition in which the preservative system for the impregnated wipe comprises potassium sorbate, citric acid, disodium ethylenediaminetetraacetate and a cationic agent selected from polyhexamethylene biguanide hydrochloride and poly[oxyethylene(dimethyliminio)ethylene(dimethyliminio)ethylene dichloride].
2. Information Disclosure Statement
Various forms of nonwoven impregnated wipes are available and have been suggested for performing a wide variety of tasks, such as for cleaning hard surfaces, cleansing the hands and other areas of the body and delivering active ingredients to various surfaces, both animate and inanimate.
In the case of nonwoven impregnated wipes adapted for cleaning hard and skin surfaces, the impregnant generally is aqueous based. Such wipes are marketed ready for use either in individual packet form or in bulk form in suitable dispensers from which individual wipes can be withdrawn as needed. Whatever the form of packaging, the wipes are stored for substantial periods of time prior to use and therefore need to be protected against microbial contamination and deterioration to which they are readily susceptible. One common method to achieve this is to incorporate a suitable chemical preservative system in the liquid composition employed to impregnate the nonwoven wipe.
Preservative systems which have been employed in a number of aqueous impregnating compositions for nonwoven wipes have included ethyl alcohol which is well known for its antiseptic effect. One such preservative system which has provided excellent results comprises sorbic acid, citric acid and ethyl alcohol. However, the ethyl alcohol generally is employed in such preservative systems at concentrations above five weight-percent of the impregnating composition.
Presently there is a trend to formulate impregnating compositions for nonwoven wipes which avoids the use of ethyl alcohol because manufacturers of wet/moist wipes perceive that many consumers would prefer alcohol-free wipes, particularly those which are primarily intended for use in personal hygiene, especially baby wash cloths for which there is a substantial market. However, a problem arises in eliminating ethyl alcohol from sorbic acid - citric acid - ethyl alcohol preservative systems for nonwoven wipes in that the combination containing only sorbic acid and citric acid does not always provide adequate protection against microbial contamination and deterioration.
U.S. Pat. No. 4,732,797 discloses a liquid preserving composition for a fibrous wiper consisting essentially of a mixture of citric acid and sorbic acid as the preservative component, water and optionally ingredients selected from skin moisturizers and fragrances.
Wipers having incorporated therein a cationic antimicrobial agent have been described, for example, in U.S. Pat. Nos. 3,264,188, 4,615,937 and 4,678,704, discussed hereinbelow.
U.S. Pat. No. 3,264,188 discloses a sanitary impregnated skin wiper for proctological use comprising a facial grade creped tissue having dispersed therethrough a mineral oil and an emulsifier such as triethanolamine oleate, which wiper may include a bacteriostatic agent, benzalkonium chloride being a preferred bacteriostatic agent.
U.S. Pat. No. 4,615,937 discloses an antimicrobially active nonwoven web wherein the antimicrobial agent is substantive both to the fibers and the binder in the web and preferably is an organo-silicon quaternary ammonium salt.
U.S. Pat. No. 4,678,704 discloses an impregnated fabric material comprising a fabric substrate, which may be woven or nonwoven, to which has been bonded an active cationic impregnant and an anionic indicator dye in combination with a further cationic component. Nonionic surfactants, chelating agents and fragrances may also be included in the impregnated fabric. Examples of the cationic materials which are disclosed are quaternary ammonium compounds, bisguanides and polymeric bisguanide such as polyhexamethylene bisguanide hydrochloride.
U.S. Pat. No. 4,587,266 discloses the use of polyhexamethylene biguanide hydrochlorides as antimicrobial agents in combination with certain amine oxides in aqueous antimicrobial compositions. The polyhexamethylene biguanide hydrochlorides are identified as being commercially available from ICI Americas Inc. under the tradename Cosmocil CQ.
A currently commercially available personal cleansing wipe product lists its key ingredients and their functions as follows:
______________________________________ KEY INGREDIENT FUNCTION ______________________________________ Demineralized Water Moisturizes tender skin Propylene Glycol PEG-75 Lanolin* Softens skin Cocoamphodiacetate Cleans and soothes skin Polysorbate 20 Methylparaben Maintains product purity 2-Bromo-2-nitropropane-1,3-diol and freshness Propylparaben Fragrance Pleasant non-irritating scent ______________________________________ *a polyethylene glycol derivative of lanolin with an average of 75 moles of ethylene oxide